Field of the Invention
This invention relates to a method of stabilizing flight of a flying body by reducing asymmetric side force, which occurs when the flying body flies at a high angle of attack with respect to an air current, so as to suppress bad or undesirable motion of the flying body. An example is rotation around the center of gravity of the flying body in a plane of an attack angle, called as flat spin, yawing or the like, due to the asymmetric side force, by means of aerodynamic means.
This invention further relates to a flying body which is stabilized in its flight by aerodynamic means.
The nature of stream of air current flowing along a fuselage of a flying body such as rocket, aircraft, and so on is characterized by a non-dimensional parameter called as a Reynolds number R.sub.e. Now assume that, for example, a slender flying body is flying at a high angle of attack with respect to an air current. If the Reynolds number based on a diameter of the flying body resides in a subcritical Reynolds number region which is lower than a critical Reynolds number region of R.sub.e =3.4.times.10.sup.5 -3.6.times.10.sup.5 laminar separation may occur in the stream or flow on left and right sides of the fuselage. If the Reynolds number resides within a supercritical Reynolds number region which is higher than the critical one, turbulent separation may occur in the stream or flow. However, the flow patterns or conditions at the both sides of the fuselage are same, so that any asymmetric side force acting on the flying body does not occur on the fuselage.
If the critical Reynolds number region, short bubbles occur only on the one side of the fuselage and its occurrence continues, and therefore an asymmetric pressure difference appears between the one side and the other side of the fuselage. This asymmetric pressure difference causes the asymmetric side force acting on the fuselage. This fact has been verified from wind tunnel experiments for a two dimensional cylindrical body and a three dimensional body designed in imitation of a head portion of a rocket.
This type of asymmetric side force occurring when the slender flying body flies at high angle of attack, for example, 30.degree.-90.degree. with respect to the air current or stream causes aerodynamically unstable flight of the flying body, rotation thereof in a plane perpendicular to the air current called as flat spin and so on, and therefore such side force is unfavorable to the actual flight of the flying body.